Moving installment date up by 8 days without clients permission

Shocking shocking shocking i have a loan with them and in the contract with them it clearly states that my first repayment date is on the 30th dec 2021 to my surprise i woke up this morning to arange my travels from jhb back to cpt as i work in jhb and they have made an early deduction. I then noticed they did send a email to me prior stating they would be collecting the money early because most companies get paid earlier. Not even may we move your installment up no they just assumed i would get paid before Christmas and debited my account. Well i only get paid after Christmas so they have left me in financial strain now before Christmas. I think this is highly aggainst our contract and if it was an issue to pay my first installment on yhe 30th Dec why not say so when applying for the loan. They have truly left me in a predicament now as my travel funds to the airport and storage of my motor vehicle are non existant and this will cause me to miss my flight and have to pay for accommodation. I have written them an email stating theese financial issues they have sprung on me and if they dont reverse my funds immediately with no 48 hour waiting period i will have to claim all the extra expences i am going to experience. They responded to my mail that they would get back to me in 4 hours i think this is against the law. There is no way moving an agreed installment date up by 8 days without permission from the other party in the contract can be legal. So i am pleeding for help what can i do to make this ill practice against consumers heard